1. Field of the Invention
The invention relates to a variable-focusing head cap assembly for a flashlight, more particularly to a variable-focusing head cap assembly that can be switched stably to provide a colored or normal light output.
2. Description of the Related Art
Referring FIGS. 1 to 3, a conventional head cap assembly for a flashlight is shown to comprise a tubular coupling sleeve 11, a parabolic reflector 111, and a cap member 10. The coupling sleeve 11 has a rear section 113 that is adapted to be mounted securely on the one end of a barrel 12 of the flashlight, and a front section 114 that extends forwardly from the rear section 113 and that is adapted to surround a lamp 121 that is mounted on one end of the barrel 12. The coupling sleeve 11 has an outer peripheral surface 115 and an annular stub 112 formed on the outer peripheral surface 115. The parabolic reflector 111 is disposed in the front section 114 of the coupling sleeve 11 and is provided with an open tail end 116 that is adapted to permit extension of the lamp 121 therein. The cap member 10 includes a tubular cap body 104, a planar lens 105, and a tubular colored light shield 101. The cap body 104 has a rear portion 107 sleeved slidably over the front section 114 of the coupling sleeve 11, a front portion 106, and an inner peripheral surface 108. The cap body 104 further has two annular stubs 102, 102' formed inwardly at the rear portion 107 to define an annular engaging groove 103 in the inner peripheral surface 108. The planar lens 105 is mounted in the front portion 106 of the cap body 104. The light shield 101 is made of a light transmissible material, and has a front end 1011 mounted on the planar lens 105 and an opposite open rear end 1012. The light shield 101 extends rearwardly from the planar lens 105 inside the cap body 104, and is adapted to permit extension of the lamp 121 therein via the open rear end 1012.
The cap body 104 is slidable relative to the coupling sleeve 11 between a fully retracted position, where the lamp 121 extends into the light shield 101 to permit generation of a colored light output, and the annular stub 112 is removed from the annular engaging groove 103, as best shown in FIG. 3, and a fully extended position, where the lamp 121 ceases to extend into the light shield 101 to permit generation of a normal light output, and the annular stub 112 engages the annular engaging groove 103, as best shown in FIG. 2.
The following are some of the drawbacks of the conventional head cap assembly:
1. The coupling arrangement between of the cap body 104 and the coupling sleeve 11 results in instability when the cap body 104 is slid along the coupling sleeve 11.
2. Friction between the annular stub 112 and the inner peripheral surface 108 of the cap body 104 can result in wearing that can lead to untimely removal of the cap body 104 from the coupling sleeve 11.
3. The annular engaging groove 103, the annular stubs 102 (102'), and the annular stub 112 only serve to mount the cap body 104 on the coupling sleeve 11 and are not capable of retaining the cap body 104 at a desired axial position along the coupling sleeve 11 to obtain a desired focusing effect.